Practice Paper 1 (Edexcel IGCSE Biology)

The following table shows changes in atmospheric carbon dioxide levels over time.

Calculate the percentage increase in carbon dioxide concentration between 1960 and 2010. Give your answer to one decimal place.

Use the data provided in part (a) to plot a graph that shows the change in atmospheric carbon dioxide levels over time.

Use a ruler to join the points with straight lines.

The diagram shows part of a food web for a desert community.

(i) Identify how many organisms in this food web are secondary consumers.

(ii) Draw the longest food chain in this food web.

(iii) Explain why most of the energy in the producers is not transferred to the hawk.

The photograph shows a fennec fox.

Drew Avery, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons

Fennec foxes live in the Sahara Desert, which is very hot. They have very large ears and a thin body.

Explain how the body shape of the fennec fox has evolved by natural selection.

Which row of the table gives the combination of factors that would lead to an increased amount of human waste being produced?

+ means increasing - means decreasing

State two ways in which pollution can reduce biodiversity.

The boxes below show a number of pollutants and the ways that they affect ecosystems.

Draw a line between each pollutant and the effect that it creates.

Pesticide levels in the water of a lake were measured at a level of 877 parts per billion.

The same pesticide was measured in the gills of a fish living in that lake and showed biomagnification by a factor of 9.75 million (9 750 000) times.

Calculate the concentration of the pesticide in the fish's gills. Give your answer in standard form.

Part (d) gives an example of biomagnification, in which the level of a dangerous compound gets higher at successive trophic levels.

Explain how biomagnification differs from bioaccumulation.

Genetic modification is a process used to improve crop yield.

Describe the role of a named vector in the process of genetic modification.

Weeds are plants that grow where they are not wanted.

Removing weeds reduces competition for mineral ions and improves crop yield.

(i) Name the mineral ion used to make chlorophyll.

(ii) Two different methods can be used to remove weeds to improve crop yield.

• Method A: pull weeds out of the ground by hand
• Method B: spray weeds with a chemical that kills them

Design an investigation to find out which method produces the highest crop yield.

Include experimental details in your answer and write in full sentences.

Cleft chin is a phenotype believed to be controlled by a single gene that has two alleles.

The dominant allele, N, codes for cleft chin and the recessive, n, allele codes for the absence of the cleft chin.

With reference to the example of cleft chin, state what is meant by the following terms

(i) Phenotype

(ii) Gene

(iii) Allele

A woman with a cleft chin has a child with a man who also has a cleft chin. The child does not have a cleft chin.

(i) Use a genetic diagram to show the genotypes of the parents, the gametes they can produce and all the possible genotypes and phenotypes of their children.

(ii) The parents then have a second child.

Calculate the probability that this child will be female and not have a cleft chin.

(iii) Sometimes a cleft chin does not develop even if the individual inherits the dominant allele.

Suggest what might cause this.

Most inherited conditions are not controlled by a single gene, but by many genes.

Describe how a scientist could distinguish between a genetic condition in rats controlled by a single gene and one controlled by many genes.

The passage describes reproduction in flowering plants.

Complete the passage by writing a suitable word in each blank space.

Flowers are organs that allow plants to carry out .............................. reproduction. The male gamete is contained within the .............................. grains. These grains are released from the .............................. , which is found on top of the filament. These grains need to land on the .............................. , the female part of the flower. Grains can be transferred by wind or by animals. These animals are often insects such as .............................. or butterflies. The petals of insect-pollinated plants are often .............................. and brightly coloured. After pollination, the grains germinate and a tube grows down the ..............................to reach the ovary. In the ovary, the gametes fuse. This process is known as.............................. .

Once the seed has been produced it can then germinate, but only in the correct conditions.

Temperature is one factor that affects the rate of germination.

Name two other factors.

A student investigated the speed of seed germination at different temperatures.

To do this they placed 20 cress seeds on a layer of moist cotton wool in a petri dish.

They set up three of these plates and placed them in different temperature conditions: one at 10 °C, one at 30 °C, and one at 50 °C.

They recorded how long it took for 15 of those seeds to germinate.

The results were as follows:

Explain the results shown in the table.

The diagram below shows the seeds shortly after germination.

Name part X and part Y of the germinating seed.

Which of these is an example of positive phototropism?

The table lists the roles of some substances found in living organisms.

Complete the table by naming each substance.

The first one has been done for you.